Re: [Kidbasic-devel] Fwd: File access?

[Ferry H. <fer...@gm...>]

I agree, keeping it simple is best.

We therefore have at least 4 new functions:

  error = fopen( filename )
  - open the file (for read and write? or separate them out?)
  - return simple true or false

  token = fread()
  - return the next token in the file
  - ignore line breaks?

  fwrite( token )
  - write the token to the end of the file

  fclose()
  - close the file

Are these 4 enough or do we need any further functions?

For example:

  feof  ??
  - way to tell when we've reached the end of the file

  fseek  ??
  - seek into the file

Cheers

/Ferry


On 11/17/06, Ian Larsen <dr...@gm...> wrote:

> I think supporting one open file (at a time) would be plenty for our
> purposes, and would make implementation a bit easier.
>
> Instead of reading characters though, I think the default function of
> a file read command should be to emulate the input statement, and read
> entire tokens.  That way a kid could type in a file:
>
> 1  aString  2.23  -3  10
> 11  24  Ian  34
>
> and calling read would return 1, then "aString", and so forth.
> We could have the data type default to string for simplicity, counting
> on the programmer to change it to the type he wants with int(), for
> example, or we could attempt to decide what the type is based on the
> token.
>
> My inclination is to return strings only, to keep things simple and predictable.
>
> -Ian
>
>
>
> On 11/16/06, Ferry Hendrikx <fer...@gm...> wrote:
> > I definitely agree that we want to avoid the classic basic approach.
> >
> > The FOPEN (and others) approach is reasonable and we should probably
> > be working at the character level, as dealing with UTF-8 etc would be
> > a real pain...
> >
> > We could take a C-like approach and have a gets(number) function? e.g.
> > returns <number> characters in a string from the currently open file
> > (until end of line?)
> >
> > Hmm.. also, do we want to support one open file or more than one?
> >
> > Cheers
> >
> > /Ferry
> >
> >
> > On 11/17/06, Ian Larsen <dr...@gm...> wrote:
> > > Actually, I haven't given it much thought, but you're right, it would
> > > be good to have that.
> > >
> > > We could have an FOPEN, FREAD, and FWRITE command.  I'm just unsure of
> > > whether they should work at the byte or character level.
> > >
> > > What I usually do is write an example program or tutorial first, and
> > > then code the commands.  It helps to focus on what is actually
> > > necessary to teach kids.
> > >
> > > Traditionally BASIC used READ and DATA statements for data input, but
> > > personally I was never crazy about that approach, most importantly
> > > because I think data should be a separate entity from the program that
> > > reads/alters it.
> > >
> > > The approach that LISP takes for file input is nice.  You can use the
> > > lisp read command on an open file to read a token, or read-line to
> > > read a line.  There's also read-char and read-byte.  This might be the
> > > best way to handle it, so kids can have a text file of data separated
> > > by white space and just read each token in one at a time.
> > >
> > > -Ian
> > >
> > >
> > >
> > >
> > > On 11/16/06, Ferry Hendrikx <fer...@gm...> wrote:
> > > > Has anyone given any thought to file access? It would be useful to be
> > > > able to open, read and write text files...
> > > >
> > > > Cheers
> > > >
> > > > /Ferry
> > > >
> >